Lens for head lamps



March 13, 1934. RgN FALGE ,950,978

LENS FOR HEAD LAMPS Filed Dec. '7. 1932 I x 7 xzx//z WWW/ Sme YIM@&Hot/144430 Patented Mar. 13, 1934 -LENS FOR HEAD LAMPS Robert N. Falge,Anderson, Ind., assignor, by mesne assignments, to General MotorsCorporation, Detroit, Mich., a. Corporation of Delaware ApplicationDecember 7, 1932, Seriai No. 646,()67

2 Clams. (Ci. 240-414) This invention has to do with lenses especiallyilute has an s-shaped outer face with a porsuch as were employed inheadlamps of the design tion 11 oi" the face between the edges of theflute described and claimed in the application of approximately parallelto the opposite face of Charles E. Godley and Robert N, Falge, SerialNo. the lens. This is further indicated in Figure 3 539518, filed May23, 1931. where ray 14: is shown passing through the por- In thatapplication there are disclosed several tion 11 of the fiute withoutbeing altered in dheadlighting systems in which each lamp Suppliesrection, while rays 16 and 18, passing through the light at the top ofthe beam on one side only, the edges of the ute, are directed sharplytothe combined beams from the two lamps proward the right. Intermediaterays will be bent 10. ducing a high beam having a substantially horiinamounts varying between these limits. With 65 zontal cutoff at the top.By depressing the beam this design rays 14 will therefore form the leftfrom one lamp a passing beam is obtained which boundary of the pattern.The advantage of this is higher on one side than on the other. In thisarrangement is that the portion 11 can be actyp of d s it is ss t th t tl mp procurately formed in the molding operation, there- 15 Viding thelight at the top of the beam on the by insuring the accurate location ofthe left right hand side of 'the road should have a fairly boundary ofthe beam and the ooncentration of sharp cutofi on its left edge with themaximum light near the left boundary. The portions of intensity as nearthe left edge as possible so that the lens :next to the risers 17 aresubject to malwhen the passing beam is used the high intensity formationin the pressing operation. such mal- 20' will reach as far down the roadas possible Wthformation may come from fillets formed at the out causingglare to an approaching driver on a corners of the glass or from saggingof the glass straight road. In that application there are Set inmolding. I have used the term llet in the Orh SeVeTal pfincples Ofdesign W c p oduce sense in which it is used in this art to mean the thedesired lateral cutofi. This invention has to rounded corners obtainedboth at the top and 25. do with a further improvement in des havingbottom of the risers 17 between flutes. The fillets 0 the same object.The result is achieved by emhave been shown on the drawing somewhatexploying flutes having faces of S-shape with a aggerated in size.Whatever be the design of portion O the face between the edges nearestfiutes the efiect of the fillets is to scatter light parallel with theopposite side of the lens so that v r a, wide angle so that such lightdoes not the rays forming the left edge of the beam pass form a part ofa useful beam. The amount of 5 through said portion while the rest ofthe light is light scattered by the fillets is so little that the d eced V y degrees o the t. This intensity is not seriousiy objectionablefrom the s iS desl'able because in p duct on it is posglare standpoint.The radius of the fillets varies sible to form the central portion ofthe fiute more substantially in production, depending upon the 35. cu tt t d p ons. Th dge temperature of the mold, glass, etc. As the rapo t sare deformed by fillets o the s s s dius becomes larger the filletintercepts the useful sin Of the %lass in mOldng, etc., and q tportionof the flute farther toward the center. y the light passing through themiS c y d The maintenance of the direction of the last rected. ray fromthe useful fiute area therefore depends In Figur@ 1 I haVB shown a frontView Of a lens upon the maintenance of the correct radius of e ody tnVentOnthe fillet. This limitation is avoided with my Figure 2 is asection on line 2-2 of Figure 1. improved form of flute as shown inFigures 2 F eu 3 is a similar section on an l r d and 3, since the lightfrom the portions of the Sca e S w a eW O the mproVed fiutes and theiiute nearest the risers is thrown fal' to the right to direction OfTays passing through them. and no attempt is made to secure an accurate190 Figur@ 4 ShOWS the application 0f y proved boundary at this side ofthe beam. Where, howflute to a CO V 16118. ever, a conventional fiute isused the radius of In Figure 1 I have shown a lens such as is used thefillet determines the portion of the lens on automobile headlampsprovided with wide through which the rays will pass that form the 50fiutes 10 over the central portion., and narrower left boundary of thebeam. Variation in radius fiutes 12 over the top and bottom portons. Theof the fillets cannot be avoided in production so specific arrangeinentof flutes forms no part of that it becomes difficult, if not impossible,to acthe present invention. curately locate the left boundary of thebeam In Figures 2 and 3 I have shown in detail the with the old styleflute. 5, design of the flutes 10. It will be noted that each Anotherdiiculty in directing the maximum intensity as far to the left aspossible arises from the fact that certain portions of the flute sagwhen the glass cools in the mold. This sag changes the direction oflight through portfons of the flute afiected. It is desirable that thissagging efiect be concentrated in portions of the flute which directlight Well to the right. In the case of the conventional fluteexperience has shown that the sag occurs in the portion of the flutewhich provides light near the left boundary of the bean. With the newflute the difficulty from sagging is largely avoided because thetendency to sag is restricted to portions of the flute next to therisers.

I have shown in Figure 4 that these fiutes may be employed withconcavo-convex lenses such as are now commonly used on automobiles. Herea portion 22 of the flute is substantially parallel with the oppositeface of the lens, while the edge portions diverge increasinglytherefrom.

I claim:

1. A molded glass lens provided over the portion thereof which isadapted to transmit light rays to define a side edge portion of the beamwith a plurality of substantially vertical flutes each having a face inthe shape of an S-curve with an intermediate portion of the face nearestto parallel with the opposed face of the lens so that the rays passingtherethrough are defiected the 'least and define said side edge portion,the portions of the flute on either side of the said intermediateportion directing light to the same side of the said edge portionwhereby a sharp cut-off is obtained at the same edge.

2. In the lens as defined in claim 1 said flute faces being connected byrisers extending substantially in the direction of the projected rays.

ROBERT N. FALGE.

